Method and apparatus for producing furnace charging mixtures including carbonaceous fuel



Apnl 16, 1963 H. G. TUFTY 3,085,947

METHOD AND APPARATUS FOR PRODUCING FURNACE CHARGING MIXTURES INCLUDINGCARBONACEOUS FUEL Original Filed Feb. 24. 1955 2 Sheets-Sheet IATTORNEYS April 16, 1963 H. G. TUFTY 3,085,947

METHOD AND APPARATUS FOR PRODUCING FURNACE CHARGING MIXTURES INCLUDINGCARBONACEOUS FUEL 24. 1955 Original Filed Feb.

2 Sheets-Sheet 2 INV ENT OR WW/ rmu ATTORN 4 Claims. c1. 2o2-a Thepresent invention relates to a method and apparatus for producingfurnace charging mixture of carbonaceous fuel with mineral materials asWell as the low temperature carbonization or coking of finely dividedcarbonaceous material.

In metallurgical and similar operations, process carbon and othermaterial have been individually measured and fed into furnaces, as forexample in the production of calcium carbide and metallic zinc. Theprocess carbon must be first prepared as by treating coal and during theheating of the coal for this purpose its plastic or agglutinatingcharacteristics create considerable difficulty in handling the samewhile the coal is going through its plastic stage prior to coking andyielding of the volatiles it contains. Known low temperaturecarbonization procedures, attempting to overcome these difficulties bypreoxidation of the coal or heating and holding the same before theplastic point is reached, have proved to be time consuming or reducedthe commercial value of by-products derived therefrom.

The principal object of the present invention is to provide meanswhereby furnace charging mixtures of process carbon and other desiredmaterial may be admixed in an efiicient and continuous manner whilecarbonizing the carbonaceous material, collecting the volatilestherefrom and providing a sponge of carbon and admixed material readyfor further processing or for introduction into a furnace.

A further and equally important object of the invention is to provide alow cost and efficient means for the continuous preparation of coke orsemi-coke by low temperature carbonization of coal by admixture withcoke breeze or the like Without utilizing additional heating mediaduring the process.

A still further and important object of the invention is the carbonizingof agglutinating coals upon an endless belt without the coal adhering tothe belt and without utilizing additional heating means for thecarbonizing process while at the same time forming an agglomeration ofsemi-coke which can be readily broken into pieces suitable forsubsequent handling.

Further objects of the invention will be in part obvious and in partpointed out in the following detailed description of the methodsemployed and the accompanying drawings of apparatus suitable forcarrying out such methods.

In the drawings:

FIG. 1 is a top view of a circular retort which can be used to carry outthe present invention.

FIG. 2 is a top view of a straight line retort for the present purpose.

FIG. 3 is a cross-sectional view taken on line 33 of FIG. 5.

FIG. 4 is a cross-sectional view taken on line 44 of -FIG. 5.

FIG. 5 is a schematic side view of a portion of the retort of FIG. 1with a side wall removed showing the apparatus for carrying out thepresent invention.

FIG. 6 is an enlarged end view of a roller forming part of the retort.

FIG. 6A is a side View of said roller, and,

FIG. 7 is a schematic side view of an apparatus incorporating the retortof FIG. 2 which retort likewise is shown with its side wall removed.

Referring now more particularly to the accompanying drawings in whichlike and corresponding parts are indicated by similar referencecharacters, numeral 1 indicates a circular casing through the bore ofwhich runs an endless conveyor 2 for supporting the material to betreated. Outlet pipe 3 is for the removal of by-product gases from theinterior of said casing while pipe 4 indicates an inert cooling gasadmission duct.

FIG. 2 discloses a similar retort having casing 5, outlet pipe 7 andinlet pipe 8, but with said casing extending in a straight line.

The interior of either of said retorts is similar to the retort shown inFIG, 5 which has casing 9, endless conveyor 10, outlet pipe 11 and inletpipe 12. Also shown is duct 13 leading through the top of said casingand ending just above said belt. A duct 14 which may be suitablyinsulated and jacketed also extends through said casing and is directedto a serrated roller 15 above said belt. Said roller has a peripheralmetallic shell 15a and a heat insulating core 15b of porcelain or thelike and a hollow shaft 150 through which a cooling liquid can bepassed. A third duct 16 likewise extends through said casing and isdirected towards a serrated roller 17 similar to and extendingsubstantially parallel to roller 15.

Casing 9 is surrounded by an insulated air jacket 18 adjacent to saidducts and terminating at outlet pipe 11. Battles 19 and 20 extend withinsaid casing towards said belt controlling the movement of the atmospherein said retort. A driven chopper 21 is mounted within said casing justprior to the outlet 22.

As shown in FIG. 7 an automatic weighing feeder 25 is connected by pipe26 having a rotary air lock 27, to an end of a preheater 28. Said duct14; is connected to the opposite end of said preheater. V

A second automatic weighing feeder 29 is connected by pipe 30 having arotary air lock 39', to an end of a superheater 31 with ducts 13 and 16connected to the opposite end thereof Casing outlet 22 is connected topassage 32 having breaker rollers 33 therein and a vibrating screen 34.Said passage continues as pipe 35 to superheater 31. A side passage 36including a rotary air lock 37 connects passage 32 with a calciner andcooler 38 having outlet 39.

In the manufacture of calcium carbide the charge to the furnacegenerally consists of parts of limestone to 65 parts of the carboncontent of the coke, by weight. To prepare this charging mixture fromraw coal and limestone dust each in the proper proportions, coal withrelatively high plastic characteristics is introduced to weighing feederZ5 and passed to preheater 28 where the coal is heated to below itsplastic forming point of approximately 640 F. At the same time limestoneis introduced to weighing feeder 29 and passed to superheater 31 whereit is heated to 1000 F. Feeders 25 and 29 are adjusted to feed theingredients in the proportions required.

The superheated limestone then passes through duct 13 onto conveyor 10forming a thin but covering layer A thereon. Further, superheatedlimestone goes from duct 16 to roller 17 and is thrown in the air intomixture with the heated coal also thrown in the air from duct 14 bystriking roller 15. This mixture falls onto the layer A of limestone onthe conveyor. The temperature of superheated limestone is selected so asto give the desired average temperature to the mixture laid on layer A.It is the purpose of the air jacket 18 to maintain this average duringthe carbonization period by preventing flow of heat from the mixingchamber out through the casing 9. This is done by maintaining a jackettemperature the same as the average temperature of the mixture. Flow ofheat through the walls is, therefore, substantially zero. By this mixingmethod the coal is very rapidly brought through its plastic state and upto the distillation temperature of the mixture or 800 F. and held thereby means of said hotair jacket.

The atmosphere in casing 9 contains only inert gas so as to prevent thecombustion of the coal. The volatiles given off are collected throughoutlet 11, and partly used to heat the preheater Z8 and superheater 31and also to provide chemical by-products. has rapidly been broughtthrough its plastic state adheres to the adjacent limestone layer A, butnot to said belt. Chopper 21 breaks up the agglutinated spongecontaining semi-coke and limestone after it is sufficiently cooled bythe introduction of an inert cooling gas by pipe 12. The sponge .thenpasses through breakers 33 to screen 34 and to calciner for completedevolatilization, if desired, and cooler 38 Where semi-coke limestonesponge emerges from outlet 39. Limestone separated by screen 34 passesthrough pipe 35 back to the superheater 31 for reuse.

Heavy tar or pitch condensate either from other sources or from thevolatiles passing from pipe 11 can be introduced through pipe 40 andsprayed on the mixture upon the conveyor and be redistilled by the heatfrom said mixture.

The foregoing procedure can be carried out utilizing coal and othermineral substances besides limestone such as metallic oxides, namely theoxides of tin, zinc, cadmium, lead, iron, chromium, calcium, copper, andmanganese. The proportions of coal to mineral substance is determined bythe ratio of process carbon to metallic oxide required. The temperatureof the oxide is de termined by the resultant temperature of the mixturedesired.

Ag-glutinating coals can be carbonized much in the same manner utilizingthe present apparatus. For this purpose coke breeze or recycledsemi-coke is introduced in superheater 31 and passes after heating toducts 13 and 16. The coal to be treated is preheated in preheater 28 andpasses to duct 14 thereafter. The superheated coke breeze or semi-cokeforms layer A on conveyor while the preheated coal fines and additionalsuperheated semi-coke or coke breeze are intermixed in air afterstriking rollers 15 and 17 respectively. The proportion of coal to cokeis governed by setting the weighing feeders and 29 to intorducesuflicient coke to meet the heat requirements of the particular coalused. The superheated coke supplies all the heat neces sary to raise thetemperature of the coal to its plastic stage whereupon some of thevolatiles are driven from the coal and pass upwardly through outlet pipe11 While the individual pieces of plastic coal adhere to the adjacentcoke breeze or semi-coke forming a semi-coke sponge. The resultantsemi-coke sponge upon reaching the chopper 21 is broken up cooled by theincoming inert gas from pipe 12 and goes through outlet 22, pastbreakers 33, over screen 34 whereupon a part thereof can pass throughpipe 35 back into superheater 31 forming part of the superheatedsemi-coke for carbonizing further supplies of coal while the balancegoes to outlet 39 and its ultimate use.

While rollers 15 and 17 are shown for throwing the carbonaceous andinorganic materials together it is to be appreciated that other forms ofapparatus can be employed for this purpose for example vibrating feederscan be used in lieu of said rollers and also the material can be droppedfrom ducts 14 and 16 onto driven horizontally rotating disc Spreaderspositioned within the retorts for this purpose. Care of course must betaken The coal which to guide the material by use of shields or the likeonto layer A.

The retorts of FIGS. 5 and 7 are presented on the drawings as in astraight line, but can equally as well be employed as circular retortssuch as disclosed in my copending application for patent, Serial No.406,944, now abandoned utilizing the circular casing 1 of FIG. 1 and anendless conveyor 2 moving around therein with ducts 13, 14 and 16directed towards said conveyor while volatiles pass out pipe 4 and inertcooling gases enter by pipe 3.

The apparatus shown and described herein is capable of considerablemodification and such changes thereto as come within the scope of theappended claims is deemed to be a part of the present invention.

What I claim is:

1. Method of producing furnace charging mixtures including carbonaceousfuel consisting essentially of preheating the carbonaceous fuel,superheating material suitable for furnace charging purposes to atemperature sufficient for heating said fuel to a plastic state uponcontact therewith, forming said superheated material as a moving layer,mixing said fuel and an additional amount of said superheated materialin space and dropping said mixture onto said moving layer while in anatmosphere preventing the combustion of said fuel to form a combinedsemi-coke and furnace charging material sponge.

2. Method of producing furnace charging mixtures including acarbonaceous fuel consisting essentially of forming a moving layer ofsuperheated non-agglu-tinating inorganic granular material, mixing acarbonaceous fuel with an additional quantity of said superheatedinorganic granular material and dropping said mixture onto said movinglayer, maintaining an atmosphere preventing combustion of said fuelaround said mixture and layer and at generally the temperature of saidmixture and thereafter separating said mixture from the non-adhereinginorganic material.

3. Method of producing furnace charging mixtures con sisting essentiallyof preheating coal, superheating an inorganic mineral to a temperaturesuflicient for the low temperature partial carbonization of said coalupon contact therewith, forming a portion of said mineral as a movinglayer, mixing the remainder of said mineral and said coal above saidlayer, dropping the resulting mixture onto said layer, maintaining anatmosphere preventing combustion of said fuel at said mixing and abovesaid layer, withdrawing the volatiles given off by said coal, coolingsaid mixture with an inert cool gas after said coal has reached itsplastic state and adhered to part of said mineral forming a spongethereof and separating the unattached mineral from said coal and mineralsponge.

4. Method for the low temperature carbonization of carbonaceous materialconsisting essentially of superheating semi-coke to a temperaturesuflicient for rendering carbonaceous material plastic upon contacttherewith and driving off at least some of the volatiles thereof,forming a moving layer of said superheated semi-coke, mixing saidcarbonaceous material with an additional amount of said superheatedsemi-coke and comingling the resulting mixture in space above saidmoving layer and maintaining an atmosphere preventing combustion of saidfuel around said mixture and said layer.

References Cited in the file of this patent UNITED STATES PATENTS

1. METHOD OF PRODUCING FURNACE, CHARGING MIXTURES INCLUDING CARBONACEOUSFUEL CONSISTING ESSENTIALLY OF PREHEATING THE CARBONACEOUS FUEL,SUPERHEATING MATERIAL SUITABLE FOR FURNACE CHARGING PURPOSES TO ATEMPERATURE SUFFICIENT FOR HEATING SAID FUEL TO A PLASTIC STATE UPONCONTACT THEREWITH, FORMING SAID SUPERHEATED MATERIAL AS A MOVING LAYER,MIXING SAID FUEL AND AN ADDITIONAL AMOUNT OF SAID SUPERHEATED MATERIALIN SPACE AND DROPPING SAID MIXTURE ONTO SAID MOVING LAYER WHILE IN ANATMOSPHERE PREVENTING THE COMBUSTION OF SAID FUEL TO FORM A COMBINEDSEMI-COKE AND FURNACE CHARGING MATERIAL SPONGE.